Spinneret for making complex hollow filaments

ABSTRACT

MELT SPINNING SPINNERETS ARE MADE BY FORMING IN A SPINNERET A HOLE OF TWO DIFFERENT DIAMETERS. A HOLLOW INSERT IS PRESS-FITTED IN THE HOLE SO THAT THE INSERT EXTENDS SLIGHTLY BELOW THE PLANE OF THE EXTRUSION FACE OF THE SPINNERET. THE INSERT HAS A COUNTERBORE COMMUNICATING WITH A SERIES OF SMALL ASSAGEWAYS EXTENDING TO THE POINT OF EXTRUSION WHERE THE PASSAGEWAYS FORM A PATTERN ADAPTED TO PRODUCE A TEXTILE FILAMENT BY THE COALESCENCE OF A CLUSTER OF SMALL STREAMS OF POLYMER AT A POINT BELOW THE SPINNERET FACE. THE RESULTING FILAMENTS HAVING A MULTITUDE OF LOBES AND AXIALLY EXTENDING VOIDS. DURING EMPLOYMENT OF THE SPINNERET, RINGS SURROUNDING THE INDIVIDUAL FILAMENTS CAN BE USED TO SUPPLY A COOLING FLUID TO SOLIDIFY THE FILAMENTS IN A CONTROLLED MANNER SHORTLY AFTER THE EMERGENCE OF THE STREAMS OF MOLTEN POLYMER FROM THE SPINNERET.

June 22, 1971 E. K. Mc INTOSH ETAL 3,585,684

SPINNERET FOR MAKING COMPLEX HOLLOW FILAMEN'I'S Original Filed Dec. 23,1966 /4' 24 Fl6.6. /f/jy/p ENTORS EUEL .McINT H PAUL T. HOWSE,

AT ORNEY United States Patent 3,585,684 SPINNERET FOR MAKING COMPLEXHOLLOW FILAMENTS Euell K. McIntosh and Paul T. Howse, Jr., Pensacola,

Fla., assignors to Monsanto Company, St. Louis, Mo. Original applicationDec. 23, 1966, Ser. No. 604,287, now

Patent No. 3,465,618. Divided and this application Feb.

3, 1969, Ser. No. 795,871

Int. Cl. D01d 3/00 US. Cl. 18-8 5 Claims ABSTRACT OF THE DISCLOSURE Meltspinning spinnerets are made by forming in a spinneret a hole of twodilferent diameters. A hollow insert is press-fitted in the hole so thatthe insert extends slightly below the plane of the extrusion face of thespinneret. The insert has a counterbore communicating with a series ofsmall passageways extending to the point of extrusion where thepassageways form a pattern adapted to produce a textile filament by thecoalescence of a cluster of small streams of polymer at a point belowthe spinneret face. The resulting filaments have a multitude of lobesand axially extending voids. During employment of the spinneret, ringssurrounding the individual filaments can be used to supply a coolingfluid to solidify the filaments in a controlled manner shortly after theemergence of the streams of molten polymer from the spinneret.

The present application is a divisional application of application Ser.No. 604,287, filed Dec. 23, 1966 (now U.S. Pat. 3,465,618).

BACKGROUND OF THE INVENTION It is well known to provide melt-spunfilaments with one or more continuous axially extending holes in orderfor the filaments to have increased cover when used in the constructionof fabrics and the like. A practical way of producing such filaments isto use an orificial grouping of a plurality of elongated segments in aspinneret permitting passage therethrough of molten fiber-formingpolymer for each filament produced, such as disclosed in US. Pat. No.3,174,364. The segments are disposed with respect to each other withineach orificial group in such a manner that the ends of the plurality ofmolten streams of polymer extruded through the segments within theorificial group coalesce endwise shortly after issuing from theorifices. There are definite limitations as to the total amount of voidthat one can obtain in a filament produced by the coalesce of smallpolymer streams. For example, when one uses nylon-66 polymer of normalrelative viscosity of, say 30-55 and conventional filament solidifyingequipment, a void percentage of the total area occupied by the filamentusually will not exceed 10-15%. Accordingly, it would be desirable toincrease the amount of void that one can obtain at practical meltspinning speeds.

It has been suggested to provide lobes or branches in textile filamentsto obtain increased cover. However, multilobal filaments possessingcross-sectional symmetry exhibit sparkles of light as can be seen fromUS. Pats. 2,939,201-2. Such sparkle is referred to as prismatic lusterbecause the filaments actually reflect and refract light as a prism. Inmany end uses filaments having such sparkle are not desirable becausefabrics made therefrom may be regarded by customers as being garish.

It has been disclosed in US. 2,965,925 to provide continuous axiallyextending holes in the lobular sections of man-made filaments. However,the prismatic phenomenon causing the garish sparkle in certainmultilobar filaments still occurs. To even a greater extent it would bedesirable to increase the amount of void in man-made filaments while atthe same time substantially to reduce or eliminate entirely the garishsparkle.

Therefore, it is an object of this invention to provide a spinneret anda spinneret assembly adapted for the practical production of man-madefilaments providing increased cover by a reduction in the amount ofpolymer employed to constitute a filament through the presence of amultitude of holes and lobes and exhibiting reduced prismatic luster.

A further object is to provide such man-made filaments as justdescribed.

Other objects may become apparent.

SUMMARY OF THE INVENTION A melt-spinning spinneret is made by cutting ina spinneret blank at least one hole of two different diameters. The holeextends from the melt face to the extrusion face with the largerdiameter-hole portion opening at the melt face and the smaller diameterhole portion opening at the extrusion face. For each hole an elongatedinsert member of two like outside diameters are shaped and force-fittedinto the holes. The length of the insert is preferably greater than thethickness of the spinneret. A counterbore is cut in the larger end ofthe insert. A series of small passageways are out between thecounterbore and the smaller end of the insert. The small passageways arearranged to produce a complex hollow textile filament by the coalescenceof a cluster of small streams of polymer normally issuing therefrom. Thespinneret is placed in a conventional spinneret block of a melt-spinningapparatus. An annular member having exhaust ports for directing a streamof coolant onto the coalescing filaments is positioned around theextending ends of the inserts to provide controlled cooling of thestreams of molten polymer forced through the spinneret orifices. Theresulting filament is multilobal and has a central axially extendinghole and a smaller axially extending hole in each of the lobes of thefilament. The total cross-sectional area of the filament is 20-50% void;and the cross-sectional area of each of the voids in the lobes beingabout 10-75% of the cross-sectional area of the central void.

DESCRIPTION OF THE DRAWING The invention can best be understood byreference to the following description taken in conjunuction with theaccompanying drawing in which:

FIG. 1 is a cross-sectional view of the spinneret assembly;

FIG. 2 is a bottom view of the spinneret plate and the distributionsystem of the coolant for solidifying the filaments;

FIG. 3 is an enlarged cross-sectional view of the annular ring in thecoolant distribution system;

FIG. 4 is a bottom view of part of a spinneret plate showing onearrangement of an orificial group for producing a filament of multiplelobes and multiple holes;

FIG. 5 is a view of a second embodiment of a group of orifices;

FIG. 6 is a cross-sectional view of a melt-spun filament produced inaccordance with the present invention.

With reference to FIG. 1 there is shown a spinneret assembly adapted formelt spinning multilobal filaments having a plurality of continuousaxially extending holes. The assembly comprises a spinneret block 1which is a part of conventional melt spinning apparatus. A spinneretplate 2 is carried in the block in sealed relationship. A plurality ofholes 3 extend from the melt face 4 of the spinneret to the extrusionface 5 thereof. The holes are provided with an upper hole portion 6 oflarger diameter and a lower hole portion 7 of smaller diameter. in eachof the holes 3 is an insert member 8. This elongated insert member hasportions of different outside diameters corresponding to upper and lowerhole portions.

A counterbore 10 extends from the larger end of the insert; and aplurality of small complex extrusion orifices 11 extend from the smallerend of the insert to establish communication with the correspondingcounterbore. The smaller end of the insert extends slightly below theplane of the extrusion face of the spinneret face.

An annular ring 12 is positioned in encircling relation with each of theportions of the insert member that extend below the plane of thespinneret plate. A source of coolant 13 is provided; and the coolant inthe form of air, steam, inert gas, water and the like is suppliedthrough a manifold distributing system 14 to the individual rings. Ascan be seen in FIG. 3 the rings have an exhaust port 15 in the form ofan inwardly opening annular slit from which the coolant exits and isdirected onto the filaments to solidify the filaments as desired. Wherea filament cor responding more closely to the shape assumed atcoalescence is wanted, one may induce a quicker quenching of the meltspun filament by providing an increased rate of heat exchange.

The exit angle a of the coolant can be any suitable angle of 0 to 80.The plane of the bottom of the insert member will normally be below thelowest point of the ring. In this manner the bottom of the insert memberwill be easily accessible for removal of any undesirable polymerdeposits that may form on the edges of the orifices during spinning.However, if the exit angle requires the ring to be below the face of thecapillaries in operation, the ring and distribution system should bedesigned so as to be recessed against the face of the spinneret duringcleaning of the insert member.

In FIG. 2 it is seen that the distribution system 14 includes a conduit16 connecting the source of coolant supply 13 to distributor 17 fromwhich the coolant is apportioned to the rings 12 via smaller conduits18.

FIG. 4 shows one preferred orificial grouping for making the multi-hole,multi-lobe filament of the present invention. In this arrangement threeelongated extrusion orifices 20 are cut in insert 8 and arranged in asegmented pattern. Six elongated orifices 21 arranged in pairscorresponding in number to the number of lobes in the filaments branchoutwardly from the annularly arranged orifices. The two branchingorifices of each pair are bent to provide closely-spaced relation at theends thereof. All the orifices of the group are spaced and arranged toprovide coalescence of the polymer streams normally issuing therefrominto filaments having multiple lobes and axially extending multipleholes.

FIG. 5 shows another preferred orificial grouping for making the type offilaments described herein. In this case six elongated extrusionorifices 22 extend through the bottom of insert 8 and arecircumferentially arranged in a segmented pattern. One orifice 23branches outwardly from each of the annular arranged orifices 22. Thebranching orifices are arranged by pairs, each member of which has endsbent together to provide closely spaced relation. Again, all theorifices of the group are spaced and arranged to provide coalescence ofthe polymer streams into multi-hole, multi-lobe filaments.

FIG. 6 shows a cross-section of a typical filament 24 obtained by usingeither of the two disclosed clusters of orificial groupings. Thefilament, if completely solid, would present scintillations of reflectedlight normally characterizing lobular filaments of this type. However,the filaments herein have a multitude of axially extending voids andexhibit considerably reduced scintillations. In many cases thescintillations may not be manifest at all. In any event, thescintillations are of a much finer scale and of a reduced intensity.Each lobe of a filament has an axially extending hole 25 which issmaller compared to the one central axially extending hole 26. The totalcross-sectional area of the filament is 20-50% void; that is, thepercentage of the total area defined by the periphery of the filamentand made up of void area is 2050. Below 20% the amount of void area isnot suflicient to provide optimum covering power in the filament; andone does not obtain a reduction in scintillation and polymer usage to bepractical. Above 50% collapsing of the filament may occur unlessexpensive care is exercised during filament formation to prevent this.The holes in the lobes are smaller than the central hole in thefilaments. It is preferred that the cross-sectional area of each of thevoids in the lobes be about 10-75% of the cross-sectional area of thecentral void in order to obtain optimum balance of greater cover andresistance to collapsing.

The spinneret can be used to produce filaments from any suitablesubstance that can be melt spun. Specific polymeric materials capable ofbeing melt-spun include: nylon-66 (polyhexamethyleneadipamide), nylon-6(polycaprolactam), nylon-4, nylon-610, nylon-l1, and theirfilament-forming copolymers thereof, e.g., nylon-6/66, 6/ 610,/ 66,etc.; polyester derived from terephthalic acid or derivatives thereofand ethylene glycol; polyethylene and polypropylene; and otherfiber-forming substances. By providing a proper molten polymerdistribution system the spinnerets herein can be used to producemulti-component crimpable filaments having a side-by-side arrangement ofdissimilar polymers.

The actual dimensions of the openings comprising an orificial groupdepend, of course, upon the characteristics of the polymer, the filamentsize or denier, the spinning speed, the temperature and nature of thecoolant, and other factors in the particular melt-spinning processes.However, a spinneret for melt-spinning nylon-66 into filaments describedabove was made from a stainless steel spinneret blank of the followingdimensions. The blank had a diameter of 2.030 inches and a thickness of0.190 inch. Six orificial groupings were arranged in the spinneret andequally circumferentially spaced. The centers of each group were on aradial line 0.50 inch from the center of the spinneret blank. Six fiatbottom round counterbores of 0.125 inch were drilled in the spinneret toa point of 0.020 inch from the face of the spinneret. From the bottom ofthe counterbore to the face of the spinneret a cluster of orifices asshown in FIG. 5 was machined using an electro-erosive technique. Thecircumferentially arranged slots were 0.003 inch thick and 0.027 inchlong. Each was spaced 0.002 inch apart. The branching slots were 0.003inch thick, 0.031 inch long, and were separated at their point ofnearest approach of 0.003 inch. The spinneret was placed in aconventional melt-spinning equipment. The coolant supply system wasinstalled as shown in FIG. 2. Nitrogen gas at 68 C. was supplied to thesix spinning points via the system at a rate of 5 cubic feet per minute.Nylon-66 polymer of a relative viscosity of 42 was melted and forcedthrough the spinneret holes. The yarn was given an orientation stretchand woven into fabric. It was noted that the yarn had a cross-section asthat in FIG. 6. The yarn provided increased cover in the fabric, and itwas noted that the yarn did not have the tiny sparkle normallyassociated with trilobal yarn.

It is apparent from the foregoing description that this inventionrepresents a substantial advance in the art of spinneret manufacture andtextile yarn made therefrom. The spinneret can be made with facility.Yarn made therefrom has a considerably large void area. This can beaccomplished at high spinning speed. The prismatic luster of the presentlobular yarn is of a much finer scale than that of a similar lobularyarn not having the internal void arrangement of the present invention.

It is apparent that many different embodiments of this invention can bemade without departing from the spirit and scope thereof; and,therefore, it is not intended to be limited except as indicated in theappended claims.

We claim:

1. A spinneret assembly for melt spinning complex hollow filamentscomprising:

(a) a spinneret block;

(b) a spinneret carried in said block and having a melt face and anextrusion face with a plurality of holes of at least two differentdiameters, the hole portion of larger diameter opening to the melt faceand the hole portion of the smaller diameter opening to the extrusionface;

(c) a hollow elongated insert member of corresponding different outsidediameters press-fitted in each of said holes, a counterbore extendingfrom the larger end thereof and a plurality of small complex extrusionorifices extending from the smaller end thereof and establishingcommunication with the counterbore, the smaller end extending slightlybelow the plane of the extrusion face and presenting a cluster ofextrusion orifices through which polymer normally flows and coalescesinto a complex hollow textile filament;

(d) an annular member having exhaust ports for directing a stream ofcoolant onto the coalescing filaments and being positioned in encirclingrelation with each of the portions of said insert member extending belowthe plane of the spinneret extrusion face; and

(e) means for supplying coolant to the exhaust ports of the annularrings.

2. A spinneret assembly for melt spinning complex hollow filamentscomprising:

(a) a spinneret block;

(b) a spinneret plate carried in said block and having a melt face andan extrusion face with a plurality of holes of at least two differentdiameters, the hole portion of the larger diameter extending to the meltface and the hole portion of the smaller diameter extending to theextrusion face;

(c) a hollow elongated insert member of corresponding different outsidediameters press-fitted in each of said holes, a counterbore extendingfrom the larger end thereof and a plurality of small complex extrusionorifices extending from the smaller end thereof and establishingcommunication with the counterbore, the smaller end extending slightlybelow the plane of the extrusion face and presenting the cluster ofextrusion orifices;

(d) a plurality of the extrusion orifices in each cluster beingelongated and annularly arranged in segmented pattern;

(e) a plurality of pairs of elongated orifices corresponding in numberto the number of lobes in the filaments and branching outwardly inspaced relation from the annularly arranged orifices and bent togetherto provide a close spaced relation at the ends thereof;

(f) the orifices being spaced and arranged to provide coalescence ofpolymer streams normally issuing therefrom into filaments havingmultiple lobes and axially extending multiple holes;

(g) an annular ring having exhaust ports for directing a stream ofcoolant onto the coalescing filaments and being positioned in encirclingrelationship with each of the portions of said insert member extendingbelow the plane of the spinneret extrusion face; and

(h) means for supplying coolant to the exhaust ports of the annularrings.

3. A spinneret plate for use in melt spinning textile multilobalfilaments having a plurality of holes extending axially along the lengthof the filaments comprising:

(a) a solid plate having a melt face and an extrusion face;

(b) at least one cluster of polymer extrusion orifices;

(c) a plurality of the extrusion orifices in each cluster beingelongated and annularly arranged in segmented pattern;

(d) a plurality of pairs of elongated orifices corresponding in numberto the number of lobes in the filaments and branching outwardly inspaced relation from the annularly arranged orifices and bent togetherto provide a close spaced relation at the ends thereof; and

(e) the orifices being spaced and arranged to provide coalescence ofpolymer streams normally issuing therefrom into filaments havingmultiple lobes and axially extending multiple holes.

4. The spinneret plate of claim 3 wherein in each cluster threeelongated orifices are annularly arranged in a segmented pattern.

5. The spinneret plate of claim 4 wherein in each cluster six elongatedorifices are annularly arranged in a seg mented pattern and one orificebranching from each of said annularly arranged orifices.

References Cited UNITED STATES PATENTS 1,933,607 11/1933 Taylor 18-8X3,262,153 7/1966 Mercer et al. 188 3,397,426 8/1968 Fujita et a1 188FOREIGN PATENTS 891,464 3/1962 Great Britain.

H. A. KILBY, In, Primary Examiner

